-I've just completed my second subaru conversion. One from an MT donor, and one from a AT donor. After searching for months to complete the first swap, I thought I would start a thread so that people considering conversion could get all the information they need in one place.
-My objectives here are not to explore abstract theory of operation, get into quibbles about the necessity of a speed sensor, or show that I know everthing there is to know. I am simply explaining my experiences and offering a step-by-step guide to completing your own conversion, and also consolidating various information sources into one page.
-I would like to thank the many great pioneers... The expirimenters and the tinkers that first attempted to rewire the subaru ECU, and shared their succeses and falures throughout the process. I've included various external links. There may be some pictures included pictures from public sources, if so I've credited these pictures to their original web address.

Why EJ22?
-The 1990-1994 EJ22 is easily accesable, relatively low cost, and high reliability. With the stock Engine Control Unit (ECU) you get great drivability at all altitudes and temperatures, great fuel economy, nice flat torque curve, and modest horsepower. The OBD-I diagnostics are not as complex as the newer engines, and any error codes can be retrieved on the fly, without special tools. Until 1996-7 the EJ22's were non-interference. Meaning that if your timing belt breaks, you will not start bashing your valves into your pistons.
-The EJ22 is realatively lightweight (about 40lb penalty over stock VW), but, because of the flat-design and short crankcase, the center of gravity is closer to the bellhousing than any of the v-6 or I-4 configurations (important to keep the front tires on the ground).
-EJ22's have running in excess of 250,000 miles with proper care, but if you need a new engine, no problem, undo 7 plugs, remove your engine, get another from the junkyard, and be back up and running for the next weekend.

Where to find your EJ22?
-I highly recommend getting a donor car. Not only will you be able to asses how your engine is running, but you will have access to all sorts of metal bits, metric fasteners, fuel lines, radiator, fans, air box, and all the wiring you could ever use in a lifetime.
-Craigslist.com has been an excellent source. I frequently see 1990-1994 Subaru Legacy's on there for $300-$1000 with crash damage, rust damage, bad transmission, bad clutch, etc. All are great donors. I found a car with 128,000 miles with a bad clutch for $500 and my friend found one that had 97,000 miles and a stripped out thermostat bolt for $300.
-Junkyard... You can get an engine from the junkyard, but for your initial conversion you will need to be sure to get a complete wiring harness for your particular engine, the ECU, radiator, fans, etc. Maybe they would sell you the complete front end of an otherwise running car.

Adapting the EJ22
-Kennedy Engineering has been making adapter and clutches for some time and has earned a good name for themselves. They make an adapter kit for the EJ22 to beetle or bus transmissions. I do, however, recommend that you order your adapter kit through a retailer. Kennedy is a great company with excellent customer service, but their lag times on direct orders is known to he high. Retail stores stock the same kit on there shelves ready for drop shipment to you.

Update--> Jim (aka "4play") just sold his subaru carcas for $150. Do the math... $300 for car - $150 back = $150 for engine, wiring, ECU, radiator, fans, intake, etc.

Let's get out hands dirty!!

Assesing the car...
When you get your donor car, you'll want to look for anything you'll need to fix. Turn the Key to on, verify that the check engine light illuminates. Start your engine, Does the check engine light stay on? If so look at troubleshooting.
Listen to your engine, do you hear any knocks, ticks or squeals that might indicate a problem? Look at the oil. Is there any evidence of water? If possible, drive your car for a week or so to get a feel for the engine's health. It's better to diagnose and fix problems now, instead of wondering why your conversion won't start later. If possible, bring your car down to get the air Conditioner drained at a service shop. If you're car has oil leaks, don't worry too much. Maybe you could talk them down on price. When I got my car it was using "a quart at every fillup". After a set of valve cover gaskets I'm down to a few drips here and there out of the cam seal. If it was burning oil, you'd be able to smell it in the exhaust, that is bad, walk away.

You might think about placing an ad for subaru parts, now, to see if you can sell off anything of value. It seems the struts are popular. Also, if your have the aluminum rims, those will sell, too. I sold the sunroof motor and seatbelt motors. The airbags would be good to sell, too. Just advertise that you are "parting out" a legacy, and people will call you for the strangest requests. Right front blinker houseing, sold that. I even threw in the left one for free! I eventually sold what was left of my legacy to a family of legacy owners as a parts car.

Side note--> please read through to the "grounding" section near the end. It might be worth the effort to do the following so you know what mode your ECU likes to run in. Tear down the dash, remove the instruments etc until you get to the ecu. As soon as you can get access to the ecu, unplug the ECU before unpluggin any other engine wires. Put the car in park (if auto) or neutral (if manual). Check the following wires from your ECU (see plugs and wire colors below)... B9, B10, A20. Use a multimeter to check for continuity to a ground. As I've said below, some ECU's are reverse of what the manual says it should be, and it might be easier to know the correct configuation beforehand.

Removing the engine...
This is the fun part. DISCONNECT THE BATTERY and start taking things apart. Unplug the mass air flow sensor (MAF), and remove the plastic intake and airbox. Disconnect the four vaccume hoses that connect to the intake. Plug the intake manifold with a rag and a rubber band. Protect the MAF from drops or knocks, set it aside for later. Drain and remove the radiator.

Unbolt the power steering pump and move it out of the way.

You did remember to have your A/C system professionally drained, right? Cut the A/c hoses, unbolt the A/C compressor, remove it. A/C compressors make good air compressors for power tools on the trail, but the weight penalty is significant. Also in this picture, the sub harness for the alternator. Unplug the alternator and unscrew the terminal connector on the alternator, move this sub harness out of the way. You see the two thottle cables? Remove those from the thottle body and move them out of the way. (Save throttle cable for later use).

Remove and label the fuel lines. The fuel line from the fuel filter is the supply, the other larger fuel line is the return. The third, smaller, fuel line is for vapors, you will not use this and it can be plugged. Also in this picture is the brake vaccume tube. Remove this from the manifold, but remember to plug the hole at some point.

At the passegner-side, front of the engine, is a charcoal canister. This is part of the fuel vapor recycling system, and can be removed. It is necessary to plug the two metal lines because your engine will still try to suck the now unfiltered air directly into the intake manifold.

There should only be 7 plugs to the engine. 3 in the back near the firewall, two (or possibly 3) on the left side of the engine and your alternator will have a plug, and a stud. A subaru repair manual will help you to remove the torque converter (if automatic), or if manual trans, just remove the bellhousing bolts. There are also two engine mount nuts on the bottom of the engine. You should unbolt these, too. While your under there, remove the three bolts from each of the exhaust headers. Remove the brace that goes from the bellhousing to the firewall. Also remove the hoses that go to the firewall for your heater core.

Above is your engine, ready for removal. (I removed the alternator for some reason, maybe it was for good reason, but you could probably just leave it on there for safe keeping.)

Borrow or rent an engine hoist. Hook a chain to the attatchment point near the bellhousing on the right-rear of the engine. Hook other end of chain to the anchor point near the left-front of the engine. Lift engine/trans just enough to get engine mounts out of their holes, wiggle and pull engine forward. Transmission and input shaft should release (drop) and engine should be free. To support the engine while in storage, I used a stack of lumber on eash side with 2x4 blocks under the exhaust flange bolts. Recommendation is to support under the oil pan, too. At this point, locate the two metal dowels the were between the engine and transmission. Remove these dowels and save them, you will need them.

Remember to grab the exhaust headers, too. I just cut the first 12 inches or so.

Removing the wiring harness...

Side note--> I talk about "two (or three)" engine plugs. Some models have three engine plugs, some models have two.

Remove dash board however you see fit, without damaging the wiring between the center of the windshield and the driver's side. You will have to remove most of the heater system, just start undoing bolts and tugging on things to see where it's stuck. Remember to undo the heater core hoses from the engine compartment, the heater core will come out with the heater. There is a plug near the center of the console on the floor for the airbags, if so equipped. I cut these first thing (while not sitting in front of it). Save the plug as airbags are a good resale item. Now, with the surface clutter taken away, you can see what a daunting task this would seem to be. Don't fret. 90% if the wires you see are junk.

Now, move to the left front fender. Undo the bolts at the top of the fender, more if you'd like. By whatever means you see fit, get the fender out of the way enough to expose the main harness running from in front of the driver's front door to the fusebox under the hood.

First locate the wires from the alternator. Follow these as far as you easily can towards the fuse box then Cut this whole section of harness out! Save this sub-harness. Locate the two (or three) big plugs that you unplugged from the engine. You want to cut everything except a line from these plugs to the ECU. Fans? Cut it. Fuse Box? Cut it. Anything else? Cut it. Just leave the main harness going to the driver's side door. You'll want to salvage the fuse box with attatched relays, the fan harness, if using subaru fans, and (again) the alternator harness.

Get in the driver's seat. Locate the ECU. The ECU is a silver metal box near the drivers side with 4 greenish-yellow plugs. This might be a good time to mark the plugs so you don't get confused later, label them on A, B, C, D as shown in red. Unplug these plugs (keep track of them), and remove the ECU for safe storage. Look up near the winshield on the left side for two big plugs with a hex head bolt in the middle of them. Use a 10mm and take the bolts out and remove the plugs. One of these plugs has most of it's wires going towards the hole in the fender and to one of the plugs on the ECU. Unplug or trim all the other wires leaving as much length on the harness as you can. There are a bunch of wires going to the fuse box, just cut em.

The left fender harness should now be removed either by pushing everything out of the hole in the body, or by pulling everything in. Set it aside for safe keeping.

Move to the right side of the engine compartment. Locate the Air Flow Meter plug (red), the rear engine plugs and o2 sensor plug (four plugs all together, blue), and the ignitor plug (green). These are the only plugs you need from this leg of the harness. They will take the shortest route back through the firewall and to the ecu. You can cut off any and all branches that don't lead to these plugs.

Move to front passenger seat. Jeesh... This is turning into a book. From the front passenger seat, find the wiring harness that comes through the center of the firewall near the center of the windshield. If you don't see where it goes through the firewall, keep removing heater components until you do, picture above. Once you find this bundle of wires, find where it Y's and goes left or right. Cut everything that goes to the right (passenger side, red line in picture above), there will be 50 or more wires here. Pull the remaining harness from the engine bay into the passenger compartment.

Keep freeing the harness until you get to the "T" intersection (red dot). You will take out most of these wires as a bundle, but you can cut everything that goes a-stray. Remember, the only thing you are salvaging here are those sensors mentioned. They go directly from the engine bay to either the computer or one of the big bolted plugs, so follow the path. To the left (driver's side) of the red dot, there will be some power wires and such, It's nice to leave some length on here, but not necessary. You can cut along the blue line here, but if you don't have to, that's fine, too. You are just looking to get all these wires out of the car for now. To the rear of the red dot, is the mostly wires to the ECU, you want to minimize cutting here for now. See the green plug (outlined in green)? There is a male and female green plug, and a male and female black plug that look identical. Trim these out and save them. These are your test mode plugs.

Okay... Hopefully you have an imagination because I'm sure I forgot something. Like I said, if it's not one of the grey sensor wires, don't worry about cutting it, you'll be adjusting for length anyway.

Stripping the wiring harness...

Let's get started... Move all your harness bits into a warm area, free from kids that'll tug on it and dogs that'll chew on it. Get some baby wipes, solvent wipes, or a wet rag to clean the wires. You'll also need a pair of sharp tipped scissors, maybe a razor, wire cutters, and maybe rubber gloves if you don't like scrubbing adhesive off your hands.

Throughout, you'll want to save all the wires; wires are expensive, especially the bigger ones. Last I saw, they were offering $.020 per pound locally for scrap wire with the insulation still on there. You may think about segregating the wires in categories: 1. yellow, yellow-red, red = power. 2. Black, black-yellow, black-white, black red = grounds. 3. everything else.

B - Left fender harness (pictured above)... Strip all tape and plastic off the harness. If you haven't already removed the fuse box, cut it out now. If you haven't removed the fan harness, cut it out now. If you haven't removed the alternator harness, cut it out now. All that should be remaining on the distal end of this harness is the two (or three) engine plugs. On the proximal end, you should have the "D" ECU plug, and the big plug from under the dash. Cut out the big plug, not the yellow ECU plug, the big bolted plug. Then, Grab onto the two (or three) engine plugs, follow the wires from these plugs up, untangling and removing all other wires. You will see that some wires have multiple splices in them, these are the grounds and the power wires. You can trim out all the grounds (Black-Yellow, Black-Red, Black White, and black). Be sure to leave enough wire from the plugs to splice into later. You may also cut out any yellow-red and yellow wires that speghetti all over the place. Work your way up to the ECU plug removing all wires that are not connected to either the engine plugs or the ECU plug. On your journey, you will find a small tan square with four wires exiting (labeled "K"). Leave 6" of wire hanging out and cut this out of the harness. These are two diodes, that you will use later on. Clean all the wires, wrap neatly, and set aside for later use.

C - Alternator Harness. Strip the plastic covering, examine and clean the wires and connectors, set it aside for later.

D - Fan Harness. In the picture above you can see the fan harness underneath where the radiator used to be. The fan plugs are outlined in blue. Just cut both sides. If you want to leave some length on there, you can disect the harness towards the driver's side, both plugs run toward the drivers side and terminate at the fuse box.

E - Fuse box relays... Next to the fuse box is a set of four black relays. You need to remove these four relays, the rack that they plug into, and as much wiring as you can easily take with it (no more than 12"). Be sure to keep the trim piece that covers the bottom of the relays for a nice neat install in your new application. Set the relays, relay rack, and trim cover aside for use later. At this point you will want to salvage save the rest of the fuses, fusible link, relays, etc for future use in whatever you need them for. Discard the fuse box, I tried to recycle it, but it's not worth the effort.

F - This is the harness atatched to the "A" plug of the ecu. Things included in this harness are the air flow meter and O2 sensor. It's easiest, I find, to start at the device plug and work your way towards the ECU plug. Once you get these two plugs fished out, then follow the other wires from the ECU plug to their termination or to whereever is convienient to cut it. It doesn't hurt to leave as much wire on here as you can easily leave.

G - This is the harness atatched to the "B" plug of the ECU. Things included here are one of the rear engine plugs(cam sensor). You will also have a blue wire that runs to the air flow meter, you might have already cut this wire to get the "A" harness out, that's okay. You will also have a short, grey sensor wire. Don't worry, you didn't screw up. This sensor wire, throttle sensor, went through the big bolted plug and had to be cut anyway.

I - The ignitor. If it hasn't fallen out already, just pull it out of the harness. It has 5 or 6 wires (depending on model year) and they are pretty long. All these wires went to the big bolted plug, which you should have already cut out. Exception, for the six wire model, is you will have a yellow-red power supply wire. You'll probably have to trim this to get the ignitor harness out.

J - The test mode, and disgnostic mode connectors. You should have these already set aside.

That wasn't so bad, Was it? Now might be a good time to clean up, salvage the last remaining things from yoru donor car, and get rid of the car. Look over the car very carefully to see what you might need, interior, seats, seatbelts, e-brake, the trunk cable is a nice morse style cable, same with the hood latch cable. Be sure to grab the thottle cables, too. You should already have the radiator and fans. Do you need metal fuel line? There are three fuel lines that run from the engine compartment down the drivers side of the car, to the fuel tank under the trunk area. There's also lots of wiring to salvage. Are you going to use any of the subaru heater components? Fan, heater core, etc. You can also salvage a few hundred dollars worth of high quality metric fasteners of all shapes and sizes. You get the idea, take everything you might need. Then scrap the car.

Mounting considerations...
Before constructing your engine harness, you should have your engine and accesories mounted. This allows you to make the harness just the right length. It might seem easy to bend a single wire, but once you get 30 wires in a bundle, wrap that in electrical tape, and cover that with corrugated plastic, a few extra inches of wire becomes a real pain in the butt.

Engine...
-The single biggest complaint you will hear about the subaru engines is how far the oil pan hangs down. There are a few options here. Some companies make a shortened oil pan (Some examples... Here, Here, Here.) This will shorten your oil pan by about 3 inches. I think shortening the oil pan is a bigger concern in the vanagon conversions because there is limited space to lift the engine.
-If you shorten your oil pan, you will need to either shorten or replace your exhaust headers, too, as they hang just as low.
-For my car, I decided to lift the engine. Initially I bought the 10 degree mounting kit, but found that 10 degrees wasn't enough for the CV flanges to clear my frame horns, so I custom made the rear transmission bracket to lift the transmission higher. A pleasent side effect was ground clearance.
-There are some very valid concerns about raising the engine at an angle like this. Oil starvation is when the oil pickup tube sucks air and you lose oil pressure, causing (among other things) your crank bearings to contact their races. My opinion is that the subaru oil pan is deep enough, and the pickup tube location forward enough, that starvation won't be an issue with the engine. I've been running for a while now without any signs of decreased oil pressure. Please take time to think about this for your particular application, I am by no means an expert on this stuff.
-Another conern is the angle of the transmission and lubrication of the pinion gear. I found if I fill the transmission to full when the transmission is level, there is plenty of oil in there, when installed, to cover the first few inches of the ring gear. Is this enough? Don't know yet.
-Last comment on mounting, Although I ran for a few thousand miles without anything other than the bellhousing bolts supporting the engine, I would recommend fabricating some kind of engine mount, if for no other reason, to buy peace of mind.
-I will not elaborate much more on mounting the engine, I am not a fabricator or engineer, nor do I brag about my abilities to weld. There are many options here, mostly limited by your imagination.

Blue - Valve cover vents, and crankcase vent. These can either go to the air intake or a separate filtered breather.
Red- This is the IAC hose. The air that goes through here MUST pass through the air flow meter first.
Yellow - I've circled the three (in this case) engine plugs. The yellow arrow points to the location of the three plugs on the rear of the engine.
Green - One note on the oil filler tube. It can be rotated 180 degrees if needed to clear obsticles.

Air Intake...
-The only absolutes on air intake, is that all air that goes through either the throttle body or the Idle Air Control (IAC), needs to go through the air flow meter.
-The air flow meter should be isolated from engine vibrations.
-My friend, Jim, used a 18" piece of 3/4" garden hose for his IAC, works like a charm.

Radiator...
-You'll want to place your radiator, more specifically the radiator fans, before building your harness.
-Again, options here are limited to the laws of physics and your imagination.
-Don't use stainless steel, mild steel, copper, or anything other than aluminum to extend your radiator hoses.
-Exception, a short piece of 1/2" copper pipe and two copper elbows make a good bypass if your not running a heater.
-The reason not to mix metals is something about the electrical potential being different, causeing the aluminum on the block to degrade. I feel that mixing 1/4lb of copper for a heater bypass isn't going to have much effect on a 200lb engine block, but larger amounts could cause problems over time. More information Here.
-Maybe someone could elaborate on the radiator mounting issues and I'll include it here.

ECU, Relay, and Ignitor mounting...
-The ECU should be mounted inside, where it won't get exposed to rain, snow, salt, water immersion, etc.
-The ECU needs ventilation to monitor barometric pressure and to keep condensation from forming.
-In a full-bodied baja, you should be just fine to mount the ECU without a protective enclosure.
-The four relays will need to find a home. There are no mounting holes on it, but be creative. Zip tied around the roll cage?
-The ignitor can be mounted either inside or outside on the firewall. Subaru mounted it perfectly horizontal, maybe there was a reason for that, maybe not.

The hole in your firewall
-Decide on a place for getting the wires through the firewall (for full bodied bugs).

Other wires...
-You might want to cnsider mounting all the rear electrical accesories before building your harness. Brake/Park lights, back-up lights, or any aftermarket guages. All can be included into the electrical harness.

Planning your harness...

Note-The conversion can be done without the following details, but for a clean installation, I recommend the following.

Now that you know where everything is going, It's time to take some measurements. I find the firewall is a good place to measure from. Take note, as your measuring, which wires will be running where and when they will need to split off. A little extra effort here will really help make a nice, neat, installation. Use a string or piece of wire and measure accurately! I'd leave no more than an inch of extra, any more than that and it will be hard to hide the extra harness.

You'll need

From hole in firewall to:
____ECU
____Relay Rack
____Rear engine plugs
____Main engine plugs
____Air flow meter
____Existing coil wire (or other 10amp fused supply from the ignition switch "on" position)
____Fuel Pump
____Starter - for start input and power supply. If your running a line directly to the battery for power supply, you will need to add a wire for "hot when starting".
____Fans, each individually if dual
____Alternator
____Oxygen sensor
____Ignitor
____Any auxillary lights, guages, senders, tachometer, placement oil light, etc. AND the location of the incomming wires for each. You don't need to measure the oil-light sender, it's already wired into the engine harness.

As you are getting these measurements, it would be wise to start drawing it out on a board.

This was my first attempt, I know lots more now and will make a much better layout on my next one.

As you can see, nails are usefull to hold the wire. You'll need nails at every junction. It's not important to imitate the shape the harness will take, but simply to replicate the lengths and the junction points. Imagine 40 wires stacked up, you'll need something to hold it together.

This would be more like what your board would look like. Each blue dot would be a nail. The options are endless here, but you get the idea. The stock subaru harness has lasted over 20 years, so it's worth your time to do this right and make it last.

Side note... I sure hope you haven't given up yet. In practice, it doesn't take a lot of time to complete, but the forethought you offer will reflect in the final results. After all the planning, final construction is a fairly mindless activity. Connect point A to point B, Connect point C to point D, Connect point E to point F, etc. This might be a good time to go buy some of your favorite beverage and turn on the music.

Soldering Tips...
-Get a good soldering gun that heats up quick
-Put the a drop of solder on the gun, that should be all you need for the tiny wires.
-Clean your tip frequently, the wood table works well for this.
-Use electrical grade solder and flux (NOT plumbers solder which will leave an acid behind and corrode)
-Don't forget shrink wrap before you solder. Don't cut your shrink wrap too long, it gets expensive quickly.
-Get a heat gun if you can to shrink the shrink wrap, then you won't risk melting the insulation with a lighter.
-Stagger your joints, if the shrink wrap fails, you don't want the joint touching another open joint.

Assembly...

For reference in the following discussions, these are the plug numbers, descriptions, and a picture of each plug. All the ridges and shapes are accurate. Don't get stuck on the numbering system, it's just as easy to look at wire colors unless there is a conflict.

Then reassemble sensor and ecu wires...

Here we go

(ECU plug position - wire color - description - destination) (if you have three engine plugs, not two, the pin # is in parenthesis)

1. The relays you see on the left of this picture are the four black relays you removed from the subaru. Use a 10 amp fuse and a 20 amp fuse. To prepare the relay rack, follow the wires from the fuses to their respective relays. You will have to trim at least one wire that runs to two relays, be sure to leave enough room to solder into, but be cautious not to leave an exposed 12v wire. You should have the 20 amp fuse going to one relay (fan), the 10 amp fuse going to another relay (fuel pump). You will have to add an in-line style fuse (20 amp) to feed both of the remaining relays (note... you can use two blade type connectors and a green 30 amp fuse from the fuse box, but you risk heating up your wires and frying your harness in case of a short). These two relays are going to act as a single ignition relay, with two switched outputs, but the same "on" signal. Once you've found a way to feed the relays, label the relays as to their function so you don't get confused later.

2. Note on the diode... Above the four relays in the diagram above is the tan diodes (labeled K in the photo far above) It looks like this : -->|-- . You will only use one of the two diodes, the other one is for the air conditioning. The wire colors are accurate, yellow to power, light green to ECU. The purpose of this is to allow the ecu to continue reading from the engine sensors for a split second after you turn the key off. Then the ECU will have "presets" to start the engine next time.

3.After prepping them, lay them on your table in the location you specified. Start following the diagram above. It should be pretty self explainitory, but keep in mind wire sizes for given loads. The alternator wires are kinda big, so soldering with an iron will be near impossible. I used a torch.

4. If you have a 5-wire ignitor (with the yellow/red wire), the yellow red wire will need 12 volts from the ignition relay.

5. Correction (Thanks, Jack511x) - The "engine plugs" as pictured are for a two plug setup. E1 is the engine side socket that fits the F26 plug, So... if you replace "F26" for "E1", it is correct for two plug setups. Otherwise, For the three plug setup things are a little different ONLY with regards to the pin numbers and wire colors. For three plug setups... A. You will connect the yellow red wire that also goes to the computer (labeled E1 - 1) to both the two yellow wires at f25 pins 5 and 9. These are redundent wires that will each separately power all the injectors. B. You will connect the other yellow/red wire that also goes to the oxygen sensor to f25 pin 12 for your CPC selenoid and the idle senenoid. This leg will also be used to go to ignitors that have the separate power (yellow/red) wire on them. C. The yellow wire (e1-4) will power your coil by connecting to the yellow/red wire at f25 pin 8 and 11.

(Note- This may seem off, and is certainly not factory, but it is the best way, in my opinion, to divide the loads. With this design, You will still separate the necessary switched loads, You will retain the ECU's ability to capture important sensor data at shutdown (this data can take up to four start/heatup/shutdown cycles to equalize and should be retained for smooth starts), but, unlike the factory wiring, the coil is directly controlled from the ignition switch instead of allowing the computer to have full control (through the "green wire" circuit). In other words, In case of major malfunction, the ECU will not have the ability to keep the engine running.

Then ground wires...

1. Wire the ground circuits as shown. All grounds go to engine except for fan grounds and "back of ECU" ground. You only need a separate ECU ground if you are not mounting it to something that's already grounded. BE SURE to have a grounding strap from your engine/trans to the chassis, though. I used a battery cable from the stater mounting lug directly to the battery.

(with the following wires, I just wired them to the outside of the harness near the ECU and also wired a ground wire to the same place so I could ground them or unground them at will. If there is not a wire at ECU plug in the location specified, then the answer is easy... Don't add a wire.)

2. B11 - Speed sensor. It would be wise to run this wire to an accesable point on the wiring harness, in case you decide to use it later. I have found you don't need it, some people swear you do. Might as well have access to it just in case.

3. B9 - This will be either a clutch interlock, a park switch wire, or empty. Don't worry if it's empty and your ECU came from a manual trans car. ONLY IF AUTOMATIC - You will ground this wire. Again, It is necessary to leave it accessible so that you can correct error codes because in the two ECU's I've done from 1990-1992, this wire has worked the opposite of what the service manual says it should.

4. B10 - Neutral switch - Manual says in AutoTrans Mode, this should be left ungrounded (not in neutral). Manual also says for Manual transmission mode - you should do the opposite - leave it ungrounded to show trans in neutral. I found this was opposite and grounded b10 in manual trans operation. You may have to experiment here after you are running.

5. A20 - AT/MT selector - Manual says Grounded for AT mode, open for MT mode. Again leave accesable to be able to switch modes if needed. These may also be reversed (ie. nonexistent wire even with AT ECU).

From here, you should have a bundle of wires resembling a harness. Tape the wires together at the junctions, only to keep it's shape. Then remove the harness from the work table and place it into your car. Hook up the engine connectors, MAF, alternator, ECU, o2 sensor etc. You'll need a functioning fuel pump for this test. Be sure to run the fuel pump (while wet) for a minute or two to get all the air bubbles out of the fuel lines. Hook up the battery last.

Don't worry about making it pretty, you'll just want to make sure the engine runs without codes, then take it out and weatherproof the harness.

** Verify that the "read memory" and "test mode" plugs are NOT connected.

1. Turn key to on verify check engine light is on, alternator light is on, and oil light is on. You should hear the fuel pump cycle for a few seconds.
2. Start it up!
3. Engine should go to a high idle that gradually slows to 500-700rpm.
4. Check oil pressure light to make sure it goes out, check alternator light and check engine light.
5. Now is a good time to sit down, reflect on your efforts, and make a donation to Shoptalkforums for hosting this advertisement-free tutorial Any sized donation multiplied by a lot of members keeps this site open.

Troubleshooting for check engine light...

The Subaru ECU offers two modes to help diagnose. "Read memory mode" and "Diagnostic Check Mode".

Read memory mode. This mode will read all codes stored on the ECU, whether or not the codes are currently active. This is important to realize. You can try to fix a code, but you won't know if the code went away until you clear the code by disconnecting the battery for a few minutes.

To activate read memory mode, you must connect the two black read memory plugs (green plugs remain disconnected) and turn the key to the on position. The check engine light should illuminate regardless if there is a code or not. If no trouble, it will flash at a constant speed. If a trouble code is present, the code will be flashed to you. Multiple codes will be flashed one after another. For example - flash, flash, flash, pause, flash, flash, long pause, flash, flash, pause, flash... repeat - would indicate the presence of two trouble codes #32 and #21.

Diagnostic check mode. The diagnostic check mode will be activated when the green plugs are connected (black plugs remain disconnected). This mode will only display active codes, not the ones stored in memory. It also will do a self diagnostic of the ECU and sensors.

With the diagnostic check mode active, turning the key to the on position will start the diagnostic test. The fans will cycle on-off-on-off-on etc. The check engine light should come on. [[[there is a specific road test procedure here, I will insert it later]]]

Trouble Codes-

"Limp mode" - There are specific instances that, when the ECU senses an incorrect or intermittant signal, it will sometimes substitube a simulated signal for a faulty sensor... in other words, it will "fail safe"ly. This allows the engine to continue to operate without permanent damage.

Code 21 - Water temperature sensor - Abnormal signal - Fail safe is to turn fan's on all the time. [[[One note here: when running an automatic mode - not in park, we got a water temp sensor failure. By grounding the b9 and telling the ecu we were in park, we eliminated the code. This is probably a result of the lack of speed sensor because the fans will vary their duty cycle with the speed of the car, interestly we didn't have a speed sensor error at all.]]]

Code 33 - Vehicle speed sensor - Abnormal Voltage (ie. no alternating signal from speed sensor when engine is above 2000rpm for 40 seconds or more when not in park or neutral) - Fail safe is to set speed to fixed value.

Code 35 - Purge control selenoid - abnormal voltage - You will not be using this valve. It is designed to recapture fuel vapors and send them into the intake manifold during idle. The valve will still be present on the intake monifold and must be in place to prevent error code.

If you have experiences using this information (good or bad), please post a reply. If you find something wrong with any of this information, I would like you to post about it so I can fix it. Please don't PM me. This page gets hundreds of hits weekly. This isn't a "hey, this guy is giving out free info and can fix it for me" post. This is the start to community conversation about the subject. If you have anything to offer, post it up, maybe someone will help. If you need more info, google is your friend. Sorry to be blunt, but I did this as an informational post and to paypack STF for all the good info on it, not to be berrated with e-mails. My surbaru conversion is going on four years and many happy miles. All I do is change the oil. I forgot most of this info long ago. Thanks.

Last edited by TimS on Mon Jul 14, 2014 3:19 am, edited 86 times in total.

Don’t ever yield your gift of dream; Your knack for gumption, too. For “It’s the crazy ones that have all the fun," if dreamers yearn to do.

It's not letting me edit the original post, but here is a snippet I need to add directly after the ECU pinouts...

The only other sensor wires you should have left that are loose from the other plugs of the harness are:

Blue and Red/Green from engine plug to igniter.
Green/White from engine plug to oil pressure light
White/Green as the second wire going to the dash for the temperature sensor.
Black/White from alternator to dash light.

VIDEO OF PULLING HARNESS...

FINISHED PRODUCT...

The beauty of this harness is that it can be built to tie into the car at two places... yes, use coil wire from VW for ignition "on" signal, then tie into power at your alternator. All relays are included for ignition, fan, and fuel pump with lead wires for the fan and fuel pump. The circuits are already sized and fused for the correct loads. The air flow meter will need to be added somewhere and the oxygen sensor. Plus is can be made custom length if needs vary.

This harness is fused already (ign relay 20a, fans 20a, fuel pump 10a) and gets power from the starter lug. Plug and play.

Replace single wire temperature sender (12 mm wrench) with 1/8" NPT 27 threaded sender from your gauge. You will find it on the front of the coolant pipe on top of the engine near the left side (when mounted in bug). If your sender has a 1/4" male spade connector it will plug right into the harness.

The belt you will need for alternator is k050275 or equivalent.

Last edited by TimS on Sat Oct 22, 2016 5:48 pm, edited 9 times in total.

Don’t ever yield your gift of dream; Your knack for gumption, too. For “It’s the crazy ones that have all the fun," if dreamers yearn to do.

Me too..... But i fear I wont find a good priced Subaru fast enough.... The itch to mod the bug for better gas milage, reliability, suspention upgrades, etc. is here & the samuri/monster bug is looking better all the time... (water cooled 30 ish mpg, disk brakes, etc, etc, etc.)
Local people on craigslist want way too much for an old subaru! $1700 for 200,000+ miles. Wrecking yards are even worse! they want $1500 for a short block & $2500 ish for a long block with rad & wire harnice.

I have done a lot of reading on Subaru conversions, and this is the first time I have seen anyone go to this much effort to put this info up. Several companies are charging a thousand bucks to make a wiring harness like this. Thanks for the great work Tim!

This is one of the best swap right-ups I have seen! Your documentation and attention to detail is great. This will make a lot of future swaps out there go much easier I'm sure, if not just for the wiring diagram. I currently have a 67 german look beetle which I had previously done a rotary swap on. I never got it going because of countless problems with the motor. I finally decided to ditch it and sell the parts to fund a subaru swap. Then I found this thread, and I am even more inspired. What makes it worse is I found a great donor car for a low price but I'm not ready for it yet. Thats what I get for jumping the gun. I want to sell the extra parts first. Thanks again for the great thread!!!

dirtygerman wrote:This is one of the best swap right-ups I have seen! Your documentation and attention to detail is great. This will make a lot of future swaps out there go much easier I'm sure, if not just for the wiring diagram. I currently have a 67 german look beetle which I had previously done a rotary swap on. I never got it going because of countless problems with the motor. I finally decided to ditch it and sell the parts to fund a subaru swap. Then I found this thread, and I am even more inspired. What makes it worse is I found a great donor car for a low price but I'm not ready for it yet. Thats what I get for jumping the gun. I want to sell the extra parts first. Thanks again for the great thread!!!

Thanks Welcome to STF. If you have questions you can PM me or write a reply here, either way. There were a few things I forgot that I rememered last time someone was asking questions, but now I forgot what is was I forgot, so if something is missing or not making sense, let me know.

edit--> oh, yes, two things I'll edit in the first post when I get a chance. The oil light wire for one. Then I wanted to make a note that there is a black/yellow wire on one engine plug that is not a ground wire. I put this note to remind me, it'll make sense when I edit it in.

Don’t ever yield your gift of dream; Your knack for gumption, too. For “It’s the crazy ones that have all the fun," if dreamers yearn to do.

Tim, Where did you get the ECU plug schematics?
I need to wire up the green test ports to my ECU, but a schematic of an '03 is difficult to get ahold of. I have the plugs, but I need to know how to wire them in so the ECU can be put in test/tune state so it can be dyno tuned.